Shanghai, China and San Antonio, US – November 14, 2025 – Duality Biotherapeutics (“DualityBio”, Stock Code: 09606.HK) today announced that the first patient with systemic lupus erythematosus (SLE) has been successfully dosed in the Phase IIa part of a Phase I/IIa clinical study (ClinicalTrials.gov Identifier: NCT06625671) of DualityBio’s BDCA2-Targeting ADC DB-2304.

This randomized, double-blind clinical study is being conducted concurrently in the United States, Mainland China, and Taiwan, China. It aims to evaluate the safety, tolerability, pharmacokinetics/pharmacodynamics (PK/PD), and preliminary clinical activity of DB-2304 for injection in subjects with SLE patients.

DB-2304 is a potential first-in-class BDCA2-targeting ADC for autoimmune diseases with global patents, independently developed based on DualityBio's proprietary immune-modulating Antibody-Drug Conjugate technology platform, "DIMAC". As the potential first immune-modulating ADC targeting BDCA2 globally, DB-2304 combines the therapeutic effects of the antibody with the potent immunomodulatory activity of a small-molecule immunosuppressant, achieving targeted delivery via the antibody moiety. This approach reduces systemic exposure to the small-molecule immunosuppressant while broadly and efficiently inhibiting the production of other inflammatory cytokines, DualityBio anticipates that DB-2304 may bring new therapeutic hope to patients worldwide.

About DualityBio

Duality Biotherapeutics (HKEX:09606) is a clinical-stage biotech company dedicated to the discovery and development of next-generation ADCs to treat cancer and autoimmune diseases. DualityBio has successfully built several cutting-edge ADC technology platforms with global intellectual property rights. Leveraging a robust pipeline, DualityBio is conducting multiple global clinical trials across 20 countries and has enrolled over 2,700 patients for multiple clinical-stage ADC candidates.

Additionally, DualityBio has established strategic collaborations with global MNCs and leading biotech innovators. As a global ADC powerhouse, DualityBio is developing novel ADCs, including bispecific ADC candidates, novel-payload ADC candidates, and autoimmune ADC candidates. For more information, please visit www.dualitybiologics.com.

Media Contact: PR@dualitybiologics.com

Investor Contact: IR@dualitybiologics.com